Studying an exceptionally rare well-aged population represents a logical progression for a new phase of the BLSA. By including a new cohort of participants who have aged exceptionally well, the BLSA will be able to utilize fully the extensive set of measures recently introduced in the study. In addition, the study of IDEAL aging is consistent with the original mission of the BLSA concerning the study of healthy aging, independent of the effects of disease. Despite excellent health at the time of enrollment only a small proportion of the nearly 500 current BLSA participants aged 80 years or older meet IDEAL criteria. By enrolling the IDEAL cohort in the BLSA their biologic, physiologic, behavioral and functional characteristics will be evaluated with using the same methods used with the current cohort who will serve as a type of control group. As is customary in the BLSA, we plan to follow this cohort for life with yearly visits. STUDY AIMS The first aim is to identify factors and characteristics that distinguish IDEAL from non IDEAL individuals. In the current BLSA, an extraordinarily wide range of information is collected on biomarkers, physiological measures, behavioral and environmental risk factors and functional and disease-related outcomes. We intend to compare the two groups to identify factors that discriminate IDEAL aging from non IDEAL aging individuals. The second aim is to identify physiological, environmental and behavioral characteristics that are risk factors for losing the IDEAL condition over several years or longer. We postulate that the mechanisms of extreme longevity probably differ from those associated with delay or escape from disease and disability. For example, we hypothesize that in older persons who escape diseases and disability, homeostatic mechanisms (integrity of anti-oxidant mechanisms, low level of oxidative damage to macromolecules, low inflammation, unimpaired autonomic reflexes, normal hormone levels etc.) are relatively intact, with little accumulated damage. DESIGN The operational definition of IDEAL aging is living until age 80 and meeting the current BLSA enrollment criteria which in brief requires the absence of chronic disease and conditions and mobility and cognitive impairment evaluated using a rigorous screening process. It can be conservatively estimated that approximately 1% of those 80 years or older are IDEAL aged individuals. IDEAL participants will be recruited from the Baltiore-Washington area, which has over 600,000 persons aged 80 years or older of whom an estimated 6,000 should be IDEAL candidates. Enrollment of IDEAL participants in the BLSA is being conducted under an R&D contract, awarded to WESTAT. Recruitment is ongoing and the first few participants have been enrolled.